Well if he was going to tell anyone, it might as well be someone he could vaguely trust who was best friends with the person one might expect him to tell, right? Of course not, but that's what he was doing out of convenience and awkwardness and a general fuck-it-all attitude that he was carrying around even more so than usual.
"She's dying, I guess." He shrugged, pulling the letter out of his pocket and handing it over so that he didn't actually have to say it. Saying the details out loud would make it real and concrete and he couldn't picture his mother bruised and bloody, lying in a hospital with all kinds of tubes and machines running her instead of her heart and brain. It was very possible that she might die.
And if she didn't, she'd still get divorced and most likely lose a lot. Judges didn't take well to murder attempts - perhaps she'd even get thrown in Azkaban. What the hell would he do then? She was, after all, the last of his family. Not caring, he pulled the flask from his pocket and took a large sip, letting the fire settle on the inside.